This invention relates to liquid skin cleansing compositions. More particularly it relates to clear liquid skin cleansing compositions comprising soap and free fatty acid.
Although toilet bars comprise the most common form of skin cleansing agents, liquid skin cleansing products have recently been the subject of considerable interest in the trade. From the consumer's standpoint, liquids have advantages over toilet bars in that they avoid the problem of washstand messiness and they have the desirable feature of personalized use in that they can be dispensed in such a manner that each user of the product only comes into contact with that portion of the product which he or she actually uses.
In the formulation of soap-based toilet bar compositions it has been desirable to include free fatty acids in the composition. Such compositions are referred to as "superfatted" soaps. The free fatty acid contributes substantially to the lathering performance of the composition and also provides a mildness benefit in that it produces a lower pH product than is obtained with fully neutralized soap, and it has an emollient effect on the skin (See U.S. Pat. No. 3,576,749, Megson et al., issued Apr. 27, 1971).
Liquid soap-based skin cleansing products are well known in the art and generally use potassium neutralized fatty acids (See U.S. Pat. No. 2,912,385, Golub et al., issued Nov. 10, 1959). These have a higher solubility than the sodium soaps which are normally used in toilet bars. Free fatty acids can be incorporated into such compositions by using added solubility agents such as synthetic surfactants and/or hydrotropes.
Liquid soaps have been formulated with mixtures of saturated and unsaturated soaps to achieve highly concentrated, physically stable systems (See U.S. Pat. No. 4,065,398, Brouwer, issued Dec. 27, 1977, and U.S. Pat. No. 2,655,480, Spitzer et al., issued Oct. 13, 1953).
The object of the present invention is to provide concentrated clear aqueous skin cleansing compositions which comprise soap and free fatty acids, and which do not require the use of additional solubilizing agents.